Solar power mobile charger can be built by tweaking digital power supply schematic. The Software/Hardware stayed almost the same as the original circuit.Current design has the same overcurrent protection and output voltage can be changed by pressing SW1. Voltage and Current are shown on LCD Display. The most obvious additions are Solar Panel and 9V 780 mAh Rechargeable lithium – ion battery.
The battery is used to store and supply the energy during low sunlight intensity periods. 7.5 V 330mA Solar Panel was the only available choice, however any other panel or combination of solar panels should work as long as it can provide minimum input voltage of at least 7.5V.The circuit can charge mobile phones or other rechargeable batteries (Don’t forget to select correct voltage) otherwise you can damage your device. As a precaution Max output voltage is limited by software to 5V.You can use mobile phone adapter to fit the design to your needs, here is my phone being charged.
The main concern for this project was phone charging current. If your phone consumes during charging more power than Solar Panel can provide you’ll drain out the 9v rechargeable battery faster than solar panel can recharge it and even in optimal conditions with direct sunlight the charger will not work. So pay attention to choosing the right components. During testing my mobile phone consumed 300mA of current while charging which is about half of rechargeable battery rating and almost equal to solar panel current output, so even without the 9V battery the charging can be done from solar panel alone.For developing a simple breadboard and Microchip Pickit2 compatible programmer were used. Programmer Header connection not shown on the schematic.